Let's clear one thing up right now: "Ideal body weight" isn't one number — it's a range. For most adults, a healthy BMI falls between 18.5 and 24.9. That means a 5'4" woman's healthy weight range is roughly 108 to 145 pounds. Devine and Hamwi both land near 120 lbs. Robinson and Miller push higher. None are "right" — they're just estimates built for different jobs. This guide breaks down why the formulas disagree, and how to find your range without getting lost in hospital math.
Developed by BMI Calculator Web Editorial Team, reviewed through our in-house RD clinical review process aligned with CDC, WHO, and NIH body composition standards.
Key Takeaways
Your "ideal" weight is a 37-pound spread, not a single digit. For a 5'4" woman, healthy BMI means 108–145 lbs.
Formula differences are real. According to a 2000 clinical review, these equations can vary by up to 19% between people of the same height.
They weren't built for your health. Devine was created to dose gentamicin in hospitals. Hamwi was a quick doctor's estimate.
Waist and context beat the calculator. Your waist under 35 inches (women) or 40 inches (men) matters more than any formula.
Age shifts the target. Research suggests for adults over 65, a slightly higher BMI (23–27) may be linked to better survival outcomes.
What Is Ideal Body Weight?
Ideal body weight (IBW) is a height-based estimate. The CDC and NHLBI use BMI to define healthy weight: 18.5 to 24.9 for most adults. But BMI is a screening tool — not a verdict on your health.
Ideal Body Weight vs. Healthy Weight Range
People use these interchangeably. They're not the same.
Ideal body weight is a formula's single number.
Healthy weight range is the BMI-based zone. It gives you room for muscle, bone, and natural variation.
A 5'4" woman's range is 108–145 lbs. The formulas cluster around 120–129 lbs. The range is what actually fits real life.
Check your baseline with our BMI calculator.
Why the Formulas Disagree
These were never meant to define your health. Walk into a U.S. hospital pharmacy: they use Devine to calculate antibiotic doses. Walk into a clinic: a doctor might use Hamwi as a quick reference.
Hamwi (1964)
Quick clinical estimate from Dr. G.J. Hamwi.
Women: 100 lbs for 5 feet + 5 lbs per extra inch → 120 lbs at 5'4"
Devine (1974)
The most cited formula — originally for gentamicin drug dosing.
Women: 45.5 kg + 2.3 kg per inch over 5 feet → ~120 lbs at 5'4"
Robinson & Miller (1983)
Later updates that bump the estimate up.
Robinson: ~123 lbs for a 5'4" woman
Miller: ~129 lbs for a 5'4" woman
Switch the height, and the math changes. For a 5'6" woman, Miller climbs to about 134 lbs. For a 5'10" man, Devine lands near 166 lbs. That's why these formulas never quite match — they were built from hospitalized patients, not gym-goers.
What our data shows: From anonymized sessions of women using our tools, most 5'4" users feel healthiest between 118–135 lbs — right in the middle of the CDC range, not pinned to a 1964 chart.
See beyond weight alone with our body fat calculator.
Healthy Weight Chart by Height
5'0": 95–128 lbs
5'2": 101–135 lbs
5'4": 108–145 lbs
5'6": 115–155 lbs
5'8": 122–164 lbs
5'10": 129–174 lbs
That's a wide spread — and that's exactly the point. Your body isn't a math problem.
How to Find Your Number — The Real Way
Step 1: Use our Adult BMI Calculator to get your category.
Step 2: Stay inside your height's range. Don't chase 120 lbs if you lift or have a larger frame.
Step 3: Measure your waist at your navel. Over 35 inches for women? That's a bigger risk signal than BMI.
Step 4: Adjust for age. After 65, a slightly higher BMI can keep you stronger, not sicker.
For age-specific adjustments, our ideal BMI calculator factors in what research shows about older adults.
Myths vs. Reality
| Myth | Reality |
|---|---|
| “Ideal weight is what I should weigh.” | It's a hospital dosing reference. Your healthy range is what matters. |
| “All calculators should match.” | They're built from different decades and patients. A 19% difference is normal. |
| “I need to weigh what I did at 25.” | Muscle loss and bone density shift healthy weight as you age. |
| “Older adults should aim for the same BMI as younger people.” | Research suggests adults over 65 with BMI 23–27 often have better survival rates. |
Frequently Asked Questions
What is the ideal body weight for my height?
It depends on the formula. For 5'4", they range from 120 to 129 lbs. Your CDC healthy BMI range is 108–145 lbs. Use the range, not the single number.
Why do different calculators give different numbers?
They use different formulas built for different jobs — drug dosing, clinical estimates, insurance tables. None were designed as a personal health target.
Does ideal body weight change with age?
The math doesn't change, but your body does. Research suggests adults over 65 may benefit from a slightly higher BMI (23–27), while younger adults follow the standard 18.5–24.9 range.
Is BMI or ideal weight better for athletes?
Neither. Both miss muscle. Body fat percentage is the better metric — which is why we pair BMI with a body fat estimator.
Should I use ideal weight as my goal?
Treat it as a rough reference. Focus on waist size, energy, and consistent habits instead of hitting 120 lbs on the dot.
Sources
Pai MP, Paloucek FP. Origin of ideal body weight equations. Ann Pharmacother. 2000.
Winter JE, et al. BMI and mortality in older adults. Am J Clin Nutr. 2014.
This article is for informational purposes only. It does not replace professional medical advice. Always consult a qualified provider. The BMI Calculator Blog Team maintains editorial independence.